CASE 13514 Published on 05.05.2016

Pulmonary cystic echinococcosis mimicking metastatic malignancy


Chest imaging

Case Type

Clinical Cases


Ammor Hicham, Boujarnija Hajar

Ibn Baja Hospital,
department of radiology,
Taza, Morocco
30000 Fes, Morocco;

20 years, male

Area of Interest Lung ; Imaging Technique Conventional radiography, CT
Clinical History
A 20-year-old male patient presented to us with chief complaints of haemoptysis and hydatidoptysis for 2 weeks, and weight loss during the past month.
Imaging Findings
Posteroanterior chest radiograph showed multiple nodules involving predominantly the right lung and airspace consolidation in the right upper lobe.
Computed tomography followed and demonstrated multiple thick-walled cystic lesions of variable size which were located predominantly at the right lung
One of these lesions (in the left upper lobe) showed an intracystic serpentine structure representing collapsed membranes (serpent sign) in relation with partial expectoration of the cyst fluid and scolices in the bronchioles.
The following differential diagnoses were considered based on imaging findings: metastases to the lungs, pulmonary hydatid disease, tuberculosis and multiple pulmonary bacterial abscesses.
Patient’s hydatid serology of blood came positive for the anti-echinococcal antibody allowing to confirm the diagnosis of pulmonary echinococcosis.
Medical therapy (including oral albendazole) was started.
Hydatid cysts are caused by a tapeworm of the genus Echinococcus. Dogs are the definitive host and humans may be infected only accidentally [1].
Liver (75%) and lung (25%) are the most commonly involved sites, other organs are involved in 10% of cases [2]. Pulmonary hydatid cysts are multiple in 30% of cases and bilateral in 20% [3].
Clinically, hydatid disease is frequently aspecific and many patients may be asymptomatic. The manifestations of cysts depend on their location and size.
Symptoms are generally caused by the compression of underlying pulmonary tissue and or complications (rupture or infection).
The cyst rupture into the bronchial tree may cause chest pain, haemoptysis or hydatoptysis [4].
Typical radiographic findings of uncomplicated pulmonary hydatid disease are single or multiple homogenous round mass with smooth boarders [5, 6]. Some characteristic radiological signs may be present: crescent sign, cumbos sign with an “onion peel” appearance, camelotte sign (water lily sign), and Monods sign (mass within a cavity). [7, 8]
Post-contrast chest CT scan may demonstrate a thin annular enhancing of the cyst wall if it is unruptured; if a daughter is present or if the main cyst is ruptured the diagnosis may be confirmed.
Routine blood tests are generally non-specific [3]. Serological tests are highly sensitive and specific.
The percutaneous aspiration of cysts can demonstrate protoscolices, hooklets and/or cyst membranes allowing establishment of the diagnosis; this procedure is too risky because discharge of contents may cause anaphylaxis.
The treatment of choice for hydatid cysts is surgical excision or evacuation [9]. Some scolicidal agents (hypertonic saline, hydrogen peroxide…) may be used intraoperatively. Medical therapy includes oral albendazole [10] and mebendazole.
Differential Diagnosis List
Pulmonary cystic echinococcosis
Lung metastasis
Final Diagnosis
Pulmonary cystic echinococcosis
Case information
DOI: 10.1594/EURORAD/CASE.13514
ISSN: 1563-4086